template arg bin search-1, C++ (gcc)

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//g++  5.4.0

#include <iostream>

using namespace std;

template<uint8_t n> struct Pred 
{
	string operator()(const string& arg) const
	{
		return Pred<n & (n - 1)>()(Pred<n & ~(n & (n - 1))>()(arg));
	}
};

template<> struct Pred<0>
{
	string operator()(const string& arg) const
	{
		return arg + "0";
	}
};

template<> struct Pred<1>
{
	string operator()(const string& arg) const
	{
		return arg + "1";
	}
};

template<> struct Pred<2>
{
	string operator()(const string& arg) const
	{
		return arg + "2";
	}
};

template<> struct Pred<4>
{
	string operator()(const string& arg) const
	{
		return arg + "4";
	}
};

template<> struct Pred<8>
{
	string operator()(const string& arg) const
	{
		return arg + "8";
	}
};

template<uint8_t n>
void todo()
    {
        cout << Pred<n>()("arg") << endl;
    }

template<int Q, int M>
void pred_selector(uint32_t n)
{
    cout << Q << " " << M << endl;
    
    if (Q == n) {
        todo<Q>();
    }
    else if (M == n) {
        todo<M>();
    }
    else if ((Q + M) / 2 > n) {
        pred_selector<Q, (Q + M) / 2>(n);
    }
    else {
        pred_selector<(Q + M) / 2, M>(n);
    }
}

int main()
{
    pred_selector<0, 255>(11);
}

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Compilation time: 1.63 sec, absolute running time: 0.08 sec, cpu time: 0.01 sec, memory peak: 3 Mb, absolute service time: 1,73 sec